Single-crystal samples of monohydrated 1-asparagine,C4 N2 03 H8. H2O, a fundamental aminoacid of the human body have been studied by Raman spectroscopy in a diamond-anvil cell up to pressures of 2.0 GPa. From the analysis of results we observed that the crystal undergoes a series of three phase transitions. All transitions are accompanied by drastic changes in the external modes showing in a clear way the transitions induced by the hydrostatic pressure.[organic crystal, aminoacid, phase transitions, hydrostatic pressure, inelastic light scattering].